Iron(I) in Negishi cross-coupling reactions.

Herein we demonstrate both the importance of Fe(I) in Negishi cross-coupling reactions with arylzinc reagents and the isolation of catalytically competent Fe(I) intermediates. These complexes, [FeX(dpbz)(2)] [X = 4-tolyl (7), Cl (8a), Br (8b); dpbz = 1,2-bis(diphenylphosphino)benzene], were characterized by crystallography and tested for activity in representative reactions. The complexes are low-spin with no significant spin density on the ligands. While complex 8b shows performance consistent with an on-cycle intermediate, it seems that 7 is an off-cycle species.

[The critical incident reporting system as an instrument of risk management for better patient safety]. / "Clinical Incident Reporting System" als Instrument des Risikomanagements für mehr Patientensicherheit.

The probability that an inpatient will be harmed by a medical procedure is at least 3% of all patients. As a consequence, hospital risk management has become a central management task in the health care sector. The critical incident reporting system (CIRS) as a voluntary instrument for reporting (near) incidents plays a key role in the implementation of a risk management system. The goal of the CIRS is to register system errors without assigning guilt or meting out punishment and at the same time increasing the number of voluntary reports.

[The implementation of risk management in a department of otolaryngology]. / Implementierung eines Risikomanagements in einer Hals-, Nasen-, Ohrenklinik.

The reasons for introducing risk management in hospitals are manifold. Not only legal but also ethical and moral aspects are of great importance.The implementation of risk management in a German department of otolaryngology is presented. Although various instruments were introduced, the main emphasis was placed on the establishment of a risk management team with the aim of prospectively and retrospectively addressing critical situations in hospital operation management and also with the goal of achieving a change of attitude towards mistakes, complications and damages in the clinic.Many aspects of the in-house processes were critically analyzed and optimization strategies were developed such as the introduction of checklists for preoperative patient identification. Furthermore the implemented CIRS has been well accepted.A meaningful objectivity of the results seems difficult. A main reason is that the index "reduction of damage and medical malpractice" is too small to make a conclusive statistical analysis. However, implementation of risk management is advisable for every ENT clinic.

Palladium(II) carboxylates and palladium(I) carbonyl carboxylate complexes as catalysts for olefin cyclopropanation with ethyl diazoacetate.

Palladium(I) carbonyl carboxylate complexes [Pd(mu-CO)(mu-RCO2)](n) (R = Me, n = 4; R = CMe(3), n = 6) and the corresponding palladium(II) carboxylates (acetate and pivalate) catalyze the cyclopropanation of olefins with ethyl diazoacetate. The performance of these catalysts is similar in terms of selectivity and cyclopropane yields, regardless of the oxidation state of the metal center. However the rates of the cyclopropanation reactions are significantly higher for the acetate based catalysts than for the pivalate derivatives, which suggests that the main catalytic species are carboxylate containing palladium complexes. Kinetic measurements show that reaction rates are independent of the olefin concentration when these are 1-hexene or styrene, but norbornene exerts an inhibitory effect. In spite of this, competition experiments indicate that the cyclopropanation of styrene is 2.2 times as favorable as that of 1-hexene for any of the four catalysts. These observations indicate that while the rate-determining formation of the intermediate palladium carbenoid species is controlled by the catalyst structure, this is followed by a rapid and less specific cyclopropanation step that is not affected by the nature of the carboxylate groups present in the catalyst. An independent test using a 1:1 benzene/cyclohexane mixture of solvents showed that the transfer of ethoxycarbonylcarbene (:C(CO2Et)H) to these molecules is unselective (relative rate of benzene/cyclohexane functionalization approximately 1.8, independent of the catalyst). This result can be interpreted as an indication of the involvement of free ethoxycarbonylcarbene in the carbene transfer step.

Studies on the atropisomerism of Fe(II) 2,6-bis(N-arylimino)pyridine complexes.

NMR spectra of free 2,6-bis(N-arylimino)pyridine (PDI) ligands displaying different substituents at the ortho and ortho' positions of the two N-aryl rings indicate that they can exist in syn (meso) and anti (chiral) configurations. These interconvert in solution at room temperature, via rotation of the aryl group. The corresponding paramagnetic FeX(2)(PDI) complexes exhibit the same kind of isomerism, a property that is thought to be important for their activity as alpha-olefin polymerization catalysts. For the first time, this has been detected by (1)H NMR and studied in solution. Although the conformational stability of the diastereoisomeric complexes varies widely (depending on the size of the substituents at the imine and the aromatic rings), a moderate degree of steric hindrance suffices to allow their chemical separation. A simple procedure is developed for the preparation of these complexes in diastereoisomerically pure form. In addition, introduction of a prochiral substituent in the pyridine ring enables positive assignment of the stereoisomers. Isomerization rate measurements of the Fe(II) complexes in solution suggest that isomerization very likely involves the dissociation of the corresponding Fe-N(imino) bond prior to the rotation of N-aryl groups. DFT calculations provide additional support to the conformational assignment as well as the dissociative isomerization mechanism.

The presence of the HLA-DRB1 shared epitope correlates with erosive disease in Chilean patients with rheumatoid arthritis.

OBJECTIVE: To assess the contribution of the HLA-DRB1 shared epitope (SE) to the radiological outcome of rheumatoid arthritis (RA) after 6 yr of follow-up in a reported series of 129 Chilean patients with established disease. METHODS: A prospective study was conducted between 1992 and 1998 using hand radiographs to assess disease outcome in a published series of patients in whom two doses of the SE were present in 20%, one dose was present in 34% and the SE was absent in 46%. At study entry, 29 of the 92 patients with hand radiographs were at Steinbrocker stages I or II (non-erosive), with a median disease duration of 2.8 yr (0.4-17). RESULTS: In 1998, 113 (87%) of the patients were alive. One hundred and eight patients underwent complete clinical evaluation. Their median age was 57 yr (range 30-81) and the median disease duration was 15 yr (6-50). We were able to study 25 of the 29 patients who had non-erosive disease at study entry in 1992. We found that 10 of 11 patients having one or two doses of the SE developed erosive disease compared with three of 14 without the SE (Yates' corrected P=0.0023, relative risk 4.24, 95% confidence interval 1.53-11.77). CONCLUSIONS: These observations support and extend the notion that the presence of the SE in one or two doses can predict the development of erosions even in RA populations in whom the SE is not as prevalent as in Caucasians.